1. Field of the Invention
The present invention relates to a data transmitting device, a data receiving device, and a data distribution system, which conduct a data communication via a network.
2. Description of the Related Art
In a conventional data distribution device, as the measures against the loss of a block via the network in data distribution, there is used an FEC (forward error correction). The FEC is a forward error correction using an error correction encoding technique, and a communication system that restores data by the aid of the redundancy added to the data to be transferred without resending the data when detecting the disposal or error of the data.
In the case where a receiver calculator successfully restores original data although the receiver calculator fails to receive several blocks, the receiver calculator transmits an affirmative acknowledgement including reception failure block information such as the identifiers or the number of blocks that fail in a reception to a transmitter calculator.
On the contrary, a transmitter calculator determines a redundancy of FEC encoding in the subsequent data transmission according to the reception failure block information that is returned from the receiver calculator. In this way, the conventional data distribution device optimizes the redundancy of the FEC according to the present receiving status (for example, refer to Patent Document 1).
Patent Document 1: JP 2002-330118 A (page 1, FIG. 4)
However, the conventional art suffers from the following problems. The conventional data distribution device must transmit the reception status or restoration enable/disenable information in each of the blocks in determination of an FEC encoding parameter. In other words, feedback from the receiver calculator side is always required. Therefore, in particular, in the case where multi-distribution system such as an IP multicast is assumed, a response from a large number of receiver calculators in each of the blocks is always required. As a result, there arises such a problem that traffic via the network is increased, or a processing load in the transmitter calculator is increased.